Oxford classification of IgA nephropathy: Broadening the scope of the classification

Is it possible to predict parameters of the Oxford classification of primary IgA Nephropathy from clinical laboratory data? Focus on the role of segmental glomerulosclerosis subtypes

INTRODUCTION

IgA nephropathy (IgAN) is the most common primary glomerulonephritis in the world and has a broad range of histological and clinical manifestations, ranging from morphologically normal to globally sclerotic glomeruli with clinical manifestations varying from isolated hematuria to end stage renal disease. This study aims to assess sensitivity, specificity and accuracy of clinical data at the time of biopsy in predicting 2017 updated Oxford classification parameters and to investigate if subtypes of segmental sclerosis (FSGS) influence clinical presentation.

MATERIAL AND METHODS

Renal biopsies from 103 patients with IgAN were analyzed. Oxford classification was updated and FSGS lesions were subclassified. ROC curves, univariate and multivariate logistic regression were used.

RESULTS

In Oxford classification, the majority of patients had mesangial hypercellularity in less than a half of glomeruli (M0), did not have endocapillary hypercellularity (E0), had segmental glomerulosclerosis (S1), had interstitial fibrosis and tubular atrophy in more than a half of the sample (T2) and had no crescents (C0). Hypertension increases the chance of M1 in 2.54x (p = 0.02). For each unit of increased creatinine, 2.6x more chances of E1 (p = 0.001). S1 is predicted by proteinuria with 75% sensitivity and 90.9% specificity (p < 0.0001). For each unit of increase in GFR, there is a reduction of 6% in the chance of T2 in relation to T0 (p = 0.0001). If hypertension, there is 5x more chances of T2 than T0 (p = 0.01). For each unit of increase in creatinine, there are 2.8x more chances of crescents- C (p = 0.003). Creatinine also showed 75.8% sensitivity and 75% specificity for prediction of C (p = 0.002). Inversely, for each unit of GFR, the chance of C is reduced by 4% (p = 0.007). Other clinical data related with C are hypertension (p = 0.03) and proteinuria (p = 0.02). To determine the role of FSGS subtypes in clinical presentation, we divided patients in S0 and S1 groups. Proteinuria was the only clinical parameter with significative difference, respectively, 0.3 (0-2.1) and 1.6 (0.02-16.2) g/24 h (p < 0.0001). FSGS subtypes related to proteinuria were cellular (p = 0.03) and peri-hilar (p = 0.02). Subtypes classically related to podocytopathies showed no correlation with clinical data.

CONCLUSION

In the future, with noninvasive methods for diagnosis of IgAN, it will be essential to predict Oxford classification parameters using clinical laboratory data for establishment of prognosis and therapeutics. We showed that Oxford classification parameters correspond to some clinical laboratory data, making this approach possible. FSGS lesions not specifically related to podocytopathies may also influence clinical parameters that affect renal disease progression.

Glomerulonephritis disease pattern at Saudi tertiary care center

OBJECTIVE

To assess changes in the pattern of glomerular diseases to help guide optimal allocation of resources, to focus future reasearch, and improve outcomes. Methods: A retrospective chart review was conducted on kidney biopsies taken between 2007 and 2016 at a single tertiary care center in Saudi Arabia (King Fahad Medical City, Riyadh) to evaluate the prevalence and pattern of glomerulonephritis (GN). Results: The most common primary GN in 102 biopsies from adult patients with a mean age of 28.9 ± 13.6 years and 40.2% female, was focal and segmental glomerulosclerosis (35.3%). Among 64 patients with systemic lupus erythematosus associated nephritis, of whom most (82.8%) were female, lupus nephritis (LN) 4 (46.9%), and (LN) 3 (32.8%) were the most common lupus nephritis classes. Conclusion: Establishing prospective GN registries from which robust diagnosis, treatment, and outcomes data can be acquired is warranted; however, registry development and maintenance are often precluded by resource limitations. Accordingly, retrospective analysis of administrative data will continue to provide important complementary information on GN epidemiology.

Expression of human T cell immunoglobulin domain and mucin-3 on kidney tissue from immunoglobulin A nephropathy patients

The aim of this study was to evaluate the expression of human T cell immunoglobulin domain and mucin-3 (Tim-3) in renal tissue from patients with immunoglobulin A nephropathy (IgAN) and without IgAN and to evaluate the difference in Tim-3 expression between them. A total of 71 patients with IgAN as IgA group and 13 patients without IgAN as control group were enrolled in the present study. Patients in IgAN accepted percutaneous renal biopsy. We examined the expression of Tim-3 in renal tissue and the serological parameters in serum from all enrolled cases. The expression of Tim-3 and serological parameters were compared between the different groups. Positive staining of Tim-3 protein was seen in 94.3 % patients with IgAN (67 out of 71), but only 15.4 % (2 out of 13) in the cases without IgAN were positive staining of Tim-3. There were significant differences between two groups in almost all serological markers, which reflect IgAN activity. There was a nearly positive correlation between pathological manifestations and expression degree of Tim-3. High immuno-reactivity of Tim-3 was found to be significantly correlated with serological grade (p < 0.001) in IgA group, but there was no such phenomenon in control group. The results showed that there was the expression of Tim-3 in renal tissue from the patients with IgAN, but rarely expression in cases without IgAN. Expression of Tim-3 was associated with the diseases' activity.

Extracapillary proliferation in IgA nephropathy; recent findings and new ideas

Context: IgA nephropathy (IgAN) is an autoimmune disorder and is the most common form of primary glomerulonephritis (GN) worldwide.

Evidence Acquisitions: Directory of Open Access Journals (DOAJ), Google Scholar, PubMed (NLM), LISTA (EBSCO) and Web of Science have been searched.

Results: It is a slowly progressing disorder that leads to end-stage renal disease (ESRD) in up to 50% of the patients within 25 years of the onset of the disease. IgAN is defined by predominant IgA deposition in the mesangial area on immunofluorescence (IF) microscopy. Its histology varies from mild focal segmental proliferation of mesangial cells to severe diffuse global proliferation with extracapillary proliferation (crescent formation). The Oxford classification, designed in 2009, is a new classification for the evaluation of morphologic lesions of IgAN. This classification, containing four pathology variables, was found to have prognostic implications. The variables included are mesangial hypercellularity (M), endocapillary proliferation (E), segmental glomerulosclerosis (S) and the proportion of interstitial fibrosis and tubular atrophy (T). However, crescents were not included in the Oxford classification.

Conclusions: In this mini-review, we describe the recent publications about the significance of extracapillary proliferation in IgAN and we conclude that, there is much controversy about the role of extracapillary proliferation as a significant prognostic factor in IgAN. Hence, it is important to re-consider crescents in IgAN patients. Therefore, we suggest further investigations on this aspect of IgAN disease.

Comment on: IgA nephropathy with early kidney disease is associated with increased arterial stiffness and renin-angiotensin system activity

We read with great interest the article by Abdi-Ali et al. entitled "IgA nephropathy with early kidney disease is associated with increased arterial stiffness and renin-angiotensin system activity" in the recent issue of Journal of the Renin-Angiotensin-Aldosterone System. In a study on 10 normotensive IgA nephropathy (IgAN) subjects with early kidney disease and 10 gender- and blood pressure-matched healthy controls, blood pressure and arterial stiffness, expressed as pulse wave velocity and aortic augmentation index, at baseline and in response to 60 min of angiotensin II (AngII) infusion were measured. They found that IgAN patients had an increased aortic augmentation index and a trend towards increased circulating renin-angiotensin system components at baseline, compared with controls.

IgM nephropathy; time to act

Implication for health policy/practice/research/medical education: Much has been published on the epidemiology and clinicopathological characteristics of IgM nephropathy, but there is little information on the etiology,pathogenesis and specific therapy of the disease. Controversy still shrouds the definition and nosologic status of the disease. Well-coordinated and concerted international efforts and collaboration between researchers in the developing and developed countries are needed to make further progress on the above aspects of the disease.

Significance of extracapillary proliferation in IgA-nephropathy patients with regard to clinical and histopathological variables

BACKGROUND AND AIM

Extracapillary proliferation (crescent) was not included in the Oxford classification, although previous attempts to correlate the crescent with clinical outcomes have produced conflicting results. In this study, we investigated the clinical and morphological significance of extracapillary proliferation in a group of IgA nephropathy (IgAN) patients with regard to the Oxford classification.

PATIENTS AND METHODS

In an observational study conducted on IgAN patients, we collected a total of 114 biopsies. We diagnosed IgAN by light and immunofluorescence for all patients.

RESULTS

Of the 114 patients, 70.2% were male. The mean age of the patients was 37.7 ± 13.6 years. The mean proteinuria was 1742 ± 1324 mg/day. The mean serum creatinine was 1.6 ± 1.5 mg/dL. Twenty-five (21.9%) patient kidney biopsies had extracapillary proliferation. We found a significant positive correlation between the number of crescents and serum creatinine (p<0.001). Furthermore, we found a positive association between the nephrotic syndrome and the total number of crescents (p<0.05). Additionally, we observed a significant positive correlation between the amount of sclerosed glomeruli and extracapillary proliferation (p=0.028).

CONCLUSION

Our findings confirm that extracapillary proliferation has a significant association with proteinuria and sclerotic glomeruli. We anticipate that extracapillary proliferation will be included in a revision of the Oxford classification of IgAN to widen the scope of the classification.

Significance of immunohistochemical findings in Oxford classification of IgA nephropathy: The need for more validation studies

Implication for health policy/practice/research/medical education: Oxford classification of IgA nephropathy (IgAN) has been validated as clinically useful tool for prognostication of individual patients with IgAN. The original classification did not address the significance of immunostaining pattern in IgAN. A subsequent study by the same authors found immunostaining data to be potentially useful in predicting some of the morphological variables of Oxford classification. The study under discussion also addresses the potential significance of these ancillary data in refining the individual prognostication in this disease. Please cite this paper as: Mubarak M. Significance of immunohistochemical findings in Oxford classification of IgA nephropathy: The need for more validation studies. J Nephropathology. 2013; 2(3): 210-213. DOI: 10.5812/nephropathol.11089.

Association of proteinuria with various clinical findings and morphologic variables of oxford classification in immunoglobulin a nephropathy patients

BACKGROUND

Immunoglobulin A nephropathy (IgAN) with nephrotic syndrome is an uncommon form of IgAN. Clinical and morphological characteristics of proteinuria in IgAN, especially when is in nephrotic range have not yet been fully examined. This study was aimed to correlate morphologic variables of the Oxford classification, and various clinical data with proteinuria in IgAN patients. We also aimed to demonstrate the significance of prevention of proteinuria as one of the important factors in progression of this disease.

METHODS

In an observational study conducted on IgAN patients, total of 114 biopsies were entered in the study. IgAN was diagnosed by light and immunofluorescence study.

RESULTS

Of 114 patients 70.2% were male. Mean age of patients was 37.7 ± 13.6 years. The mean of proteinuria was 1742 ± 1324 mg/day. Also mean of serum creatinine (Cr) was 1.6 ± 1.5 mg/dL. Of 114 patients, 11(9.6%) had nephrotic range proteinuria. In this study, there was a positive correlation between proteinuria and serum Cr, peri-glomerular fibrosis or interstitial fibrosis. There was a positive association between proteinuria and totally sclerotic glomeruli too. There was also a positive association between the amount of fibrous crescents and the level of proteinuria. Nephrotic proteinuria could just be seen in male patients. Also, nephrotic syndrome had a positive association with the number of crescents.

CONCLUSIONS

Our findings firstly support the prognostic value of crescent due to its association with proteinuria and secondly imply the importance of treatment of proteinuria to prevent progression of IgAN.

Immunoglobulin A Nephropathy and Malaria falciparum Infection; a Rare Association

Glomerular involvement occurs as a rare form of renal manifestation in Plasmodium falciparum malaria. Here, we report a rare case of falciparum malaria-associated IgA nephropathy. A 28-year-old man was admitted because of fever and abdominal pain. Ultrasound and computed tomography (CT) showed right kidney pyonenphrosis. Despite placing a nephrostomy tube, fever continued. Repeated CT was in favor of focal pyelonephritis. In addition, peripheral blood smear suggested malaria. Anti-malarial drugs were initiated and right nephrectomy was performed. One year after recovery from malaria, a persistent rise in serum creatinine was detected. A left kidney biopsy showed mesangial proliferation and dominant IgA deposits in immunofluorescence study while C1q was not deposited. The impression was IgA nephropathy with M1E0S0T0 of Oxford classification. The patient was prescribed a combination of low dose prednisolone and angiotensin converting enzyme inhibitor. Six months after treatment serum creatinine decreased from 1.6 mg/dL to 1.3mg/dL and urine abnormalities were disappeared. Our findings suggest that malaria infection might be associated with IgA nephropathy.